SpaceX Falcon 9 FT - ORBCOMM-2 - Dec. 21, 2015 (Return To Flight) DISCUSSION

[Bynaus]

So if the booster gave around 170GJ of energy to the payload (0.5*125*1.65²)then how did it manage to come back to the launch site? Is the 120GJ  an understatement or was the payload significantly lighter than 125 tonnes?

of course the payload is significantly lighter than 125 tonnes. more likely, lighter of even 12.5!

For the booster, the payload Musk is referring to is the fully fueled upper stage (plus actual payload, i.e., satellites, plus fairing).

[cartman]

After reading Elon's article better, the 200GJ number is for the missions that landed at sea. So at what speed did the orbcomm stage sep happen?
edit: stage sep happened at 5804km/h=1.61km/sec
kinetic energy is ~160GJ, still significantly more than 120. Payload mass should get to ~92 tonnes for kinetic energy to approach 120GJ

[vaporcobra]

Hi everyone, I am truly elated and happy to have today be the day of my first NSF forums post. It was asked several times before but essentially ignored: where might one find the post-launch teleconference? Has it been recorded and/or is it available at all?

[ugordan]

Remote pad camera view:

[kevinof]

Fantastic night for everyone.

My 15 year old, who is unsure of where he wants to go in life, watched the launch, landing and the cheering of all the (mostly) young SpaceX staff and said - "Dad, I want to do that! I want to build rockets and do science stuff.". It's great to see the hundreds of young engineers and others so engaged in the success of Space X.

Anyway what are the odds that Musk and Co can do the same with Dragon 2? Pop it back on a landing pad just like a helicopter landing. I'd say after this they are highly likely to pull it off.

[hrissan]

After reading Elon's article better, the 200GJ number is for the missions that landed at sea. So at what speed did the orbcomm stage sep happen?
edit: stage sep happened at 5804km/h=1.61km/sec
kinetic energy is ~160GJ, still significantly more than 120. Payload mass should get to ~92 tonnes for kinetic energy to approach 120GJ

There is a moment in SpaceX webcast where the commentator announces that the second stage acceleration is 4.7 gee. May be the second stage was not fully fueled to ease 1st stage job and allow land landing?

At 30:30 on this video:

T+7:30, 4.7G acceleration, speed on the right screen corner is 13000km/h. Could someone with experience calculate S2+payload mass based on this?

[Seer]

What is the payload hit for the return to pad landing over the barge landing? Anyone calculated it?

[dodo]

Layman opinion here. While watching the launch, I also heard the mention of 4.7g and, at that time, the speed display was changing by 100 km/h about every second (eyeball time measure; maybe a bit slower). 100km/h per second is about 2.8g; I understood Mr. Insprucker meant that the target acceleration (by SECO) was to be 4.7g. On rewatching the webcast you can hear him speaking about the rocket "building up" the 4.7g.

[Jet Black]

Another view of the second stage engine seen during the middle of satellite deployment.

Enhanced image of first stage. There seems to be smoke or vapour coming from the base.

Final view of first stage seen in broadcast (enhanced).

If you look at this landing video, at about 5s there is a little burst of something from the left of the rocket, near the base.

https://www.youtube.com/watch?v=ZCBE8ocOkAQ&feature=youtu.be&app=desktop

then there was that little fire under the rocket too. I wonder if they're related.

[Ben the Space Brit]

FWIW, my guess about the fire post-MECO4 is that it was either residual RP1 burning off as it flowed across the hot nozzle of the centreline engine or, possibly, a very small RP1 leak from one of the joins on the prop hoses at the very last few moments caused by the repeated extreme pressure changes of the engine start/stop cycles.

[Hankelow8]

What an amazing time this has been. The forum was on fire with excitement, noticed lots of new and recent joiners on the site. As I have said before nothing can match this site for information on all aspects of Astronautics.

Space X has now moved the goal posts to a new dimension, gone are the old "expensive ways " to launch.

All other companies will have to seriously re-think their future plans otherwise they will be blown away.

Interesting times ahead me thinks !!

As Punch says "That's the way to do it". 

[Maciej Olesinski]

One more thing to go - daylight landing

[Ben the Space Brit]

Just out of interest, do Falcon-9s have tail numbers like ULA boosters? If so, for the record, what was the number of this booster?

FWIW, I believe that this may be around the 23rd or 24th off of the lines of all Falcon-9 models.

[fast]

Layman opinion here. While watching the launch, I also heard the mention of 4.7g and, at that time, the speed display was changing by 100 km/h about every second (eyeball time measure; maybe a bit slower). 100km/h per second is about 2.8g; I understood Mr. Insprucker meant that the target acceleration (by SECO) was to be 4.7g. On rewatching the webcast you can hear him speaking about the rocket "building up" the 4.7g.

I think those on screen speed indicators not entirely correct. At the beginning of second stage burn speed did not change much when up to 1g was expected.
Probably SpX just hiding sensitive info. If indicators would be precise, competitors will be able to calculate a lot about F9 real specs and performance.   

[ugordan]

At the beginning of second stage burn speed did not change much when up to 1g was expected.

Gravity losses due to a pretty much vertical trajectory at that point?

[kirghizstan]

How awesome would a picture of a florida sunrise with the Aluminum Falcon in the foreground be

[Jarnis]

Just out of interest, do Falcon-9s have tail numbers like ULA boosters? If so, for the record, what was the number of this booster?

FWIW, I believe that this may be around the 23rd or 24th off of the lines of all Falcon-9 models.

F9-021 if I'm not mistaken.

[OxCartMark]

I just looked at the order of the headlines in Google News.  I don't think I've given Google any biases that affect the ranking(?).

- Deadly attack on U.S. forces shows the Afghan war is far from over

- Hillary Clinton camp to Donald Trump: 'Hell no' on apology

- Elon Musk's SpaceX returns to flight and pulls off dramatic, historic landing

- Oregon woman held in Las Vegas Strip sidewalk rampage drove with license suspended

Google News headlines the morning after:

- Your Tuesday Briefing: Sandra Bland, Taliban, SpaceX  (New York Times)

- Donald Trump Launches Vulgar Attack Against Hillary Clinton

- Britain says deploying military personnel to Afghan Helmand province

- SpaceX Makes History: Falcon 9 Launches, Lands Vertically  (NBC News)

- Refugee and migrant arrivals in EU pass 1 million in 2015: UN

[DecoLV]

"Good Morning America" (ABC) gave it about 15 sec., showing the landing. Reporter explained that re-use could lower costs "for space tourism" 

[laszlo]

Space X has now moved the goal posts to a new dimension, gone are the old "expensive ways " to launch.

All other companies will have to seriously re-think their future plans otherwise they will be blown away.

Not quite. What they've actually done is to spend more money on fuel, labor, etc. to get a used rocket stage back intact on the ground. That's quite an impressive technical feat, but economically it's still a drag on the bottom line that has to be covered either by the customer or SpaceX. So far it's a new expensive way to launch.

If and when the recovered boosters can be cheaply refurbished to be reliable enough to convince customers to go with used boosters, THAT'S when the old expensive ways will be gone - if there are enough light payloads to allow SpaceX to accumulate used boosters and customers to use them.

This was an impressive technical achievement, but so far it's still an R&D investment, not an economic paradigm shift. Kudos to the technical team, but hold the wake for the competition once the economics are proven.